The newer sketch covers from Marvel and DC finally have a wonderful stock that isn't as slick as most of their earlier ones. Basically any new Marvel cover with the red bottom 'Re-Evolution' border or the DC with the top blue New52/'We Can Be Heroes' border is great stock to work on.

That's good to hear that people are finally catching on, Haha. First time I tried to color on a slick cover and discovered that it just wasn't going to go down the way I wanted it to, I crumbled in despair.